Same issues here! My iPhone 11 has no cellular data (shows full bars until you try to make a call, browse the net or open an app) horrific reception if you manage to get on a call, super fast battery loss (I feel like I have a landline phone again how frequently it’s plugged in to charge) tried all suggestions for fixing/troubleshooting without any success. airplane mode toggle on/off cellular data toggle on/off network settings reset hard reset I put my sim in an old iPhone 6s and it works fine, so it’s 14.4 on iPhone 11 issue. I created this account just so I can reply to this thread! I have been having issues for quite sometime and thought it was my provider so I switched from Optus to Telstra and it didn’t make any difference! So glad I found this thread. Any update on a solution? A previous reply notes to take phone to Apple and it will be replaced? Anyone else done this successfully?

**EDIT*** Have spent all morning on the chat and phone to apple trying to resolve this issue. I had a Norton subscription on my phone and the VPN was overriding everything on cellular data, I could t even turn it off in settings. Once Norton app was deleted, everything started to work normally again!! Not sure who this may help, but my phone seemingly works again after the security app on my phone was removed. Apple advice - If you don’t want to remove the Norton app, your best option is to contact the app developer and provide your feedback and see if they can troubleshoot you through a solution. Goodluck